Planet surface material recreation
A good material consist of the following element.


Diffuse map with no harsh reflection, usually resembling photos taken on an overcast day.
Normal map to improve the surface texture, usually to push the limitation of a lower polygon mesh to look really high in density.
Specular / Roughness map to provide information where the object is more reflective than other areas. Real material in the real world don't reflect in a linear fashion or have the same roughness over all of it's surface.
Ambient Occlusion map to improve cracks and fine crevices. Giving a fine touch to realism.
Dirt and Grime map added to improve on wear and tear like scratches, can be bundle with or multiplied with Specular map.


Note : If you look at the image you posted the planet you aim to achieve has an atmosphere. By looking at the blue glow around the planet we know that atmosphere exist in that image. The moon for example will never have a blue band of glow, because it doesn't have atmosphere. You will want to look into how atmosphere affects color at a glancing angle, normally the word used in CGI is "fresnel" effect.

And remember due to the harshness of the way sun light reflect off a close by celestial object like a planet. Stars would be very difficult to see with the naked eyes. That is to say not only your material but your understanding of how light behave in the background is needed to communicate realism.